JP2017013479A - Food packaging film, and packaging body using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film facilitating taking out a food with high viscosity such as bean jam, Miso and bread dough without adhering to the film, without forming a water-repellent particle layer, transparent, and excellent in visibility.SOLUTION: A food packaging film is a co-extrusion multilayer film comprising two or more layers, arranged with a gas barrier layer and a heat seal layer. The heat seal layer is configured from a polyolefin resin or a resin composition having a polyolefin resin as the chief ingredient. A three-dimensional surface roughness Ra per 6700 μmof the heat seal layer surface is 300nm-1,000nm, and the heat seal layer is arranged on a content side when making a packaging body for filling content using the film.SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to a film and a packaging body for packaging food contents with high viscosity, such as eggplant, miso, and bread dough, in which the contents are not significantly adhered to the inner surface of the bag and the contents can be easily taken out.

  In recent years, switching from cans to plastic film bags has been carried out as commercial packaging for foods such as eggplant and miso.

Conventionally, a pillow bag or a double bag package in which two films are stacked has been used. For example, Patent Document 1 discloses a commercial or industrial product that fills 2 kg or more of liquid, semi-fluid, paste, etc. Multiple bags for use are disclosed. Patent Documents 2 and 3 include double bags filled with liquid paste or liquid form such as flour paste, kneaded rice cake, chocolate, margarine, liquid egg, soft drink, etc., and Patent Document 4 is heated to 80 ° C. or higher. Thus, double bags filled with liquids such as sauce, soup, soup, margarine, and viscous foods are disclosed.
However, in these packaging bags, when foods with a viscosity of 1 × 10 ⁵ mPa · s or more such as eggplant or miso are packaged, the contents adhere to the inner surface of the film, and the contents are completely removed. In other words, the contents had to be scraped or squeezed out of the film, and the workability was very bad.

  Further, in Patent Document 5, a release agent containing a solid and liquid surfactant in a sealant layer is added to a resin as a film for filling and packaging high-viscosity contents such as kneading paste, shortening, jam, and mayonnaise. A film produced by the inflation method is disclosed, and Patent Document 6 discloses a packaging bag having a good peelability of viscous contents such as mayonnaise, cream, jam, etc., and an HLB value of 2.0 or less in the seal layer. A film prepared by an inflation method by adding a release agent composed of a fatty acid ester having zero hydroxyl groups is disclosed.

  However, in films in which these release agents are added to the seal layer, the release agent consisting of a surfactant migrates from the surface of the film to the inside of the contents due to high-temperature and high-pressure sterilization after food packaging and long-term storage. The type disappears.

  If the releasability of the content is insufficient or disappears, it will adhere to the film when the content is removed, reducing the usable amount of the content, and removing the adhered content again For this reason, there are problems such as an increase in labor and processes and a difficulty in recovering the packaging material after use as a material, and improvement is required.

  In addition, contents such as jelly confectionery, pudding, yogurt, liquid detergent, toothpaste, curry roux, syrup, petrolatum, face wash cream, face wash mousse, and other solid, semi-solid, liquid, viscous, and gel-like substances adhere to the packaging material. As a non-water-repellent film, Patent Document 7 discloses a film containing a filler layer in a sealing layer and coated with water-repellent particles on its surface, and Patent Document 8 discloses hydrophobic oxidation on a heat-softened resin substrate. Each film is disclosed in which fine particles are applied and cooled and solidified.

  However, these films require a step of applying and drying water-repellent particles or hydrophobic oxide fine particles separately from film formation, which increases the number of manufacturing steps and increases the manufacturing cost. Further, the particle layer formed on the film surface has a problem that the transparency of the film is poor and the visibility of the contents becomes insufficient.

JP 2003-305783 A JP 2003-335302 A JP 2003-26234 A JP 2007-15725 A WO2012 / 144536 JP2013-112410A JP2013-75715A JP 2014-968 A

  The present invention is intended to solve the above-described problems of the prior art, and the object of the present invention is to form a high-viscosity food such as eggplant, miso, and bread dough on a film without forming a water-repellent particle layer. An object of the present invention is to provide a transparent and excellent visibility film that can be easily taken out without being worn, and a package using the film.

As a result of intensive studies on the above problems, the present inventor has found that the problem can be solved by producing a film having a specific configuration, and has completed the present invention.
That is, the present invention is a coextruded multilayer film comprising two or more layers, in which a gas barrier layer and a heat seal layer are disposed, wherein the heat seal layer is a polyolefin resin or a resin composition containing a polyolefin resin as a main component. When the three-dimensional surface roughness Ra per 6700 μm ^{2 on the} surface of the heat seal layer is 300 nm or more and 1000 nm or less, and a package for filling the contents using the film is prepared, It exists in the co-extrusion multilayer film characterized by the said heat seal layer being arrange | positioned at the contents side.

  According to the present invention, in a plastic package containing high-viscosity foods such as eggplant, miso, and bread dough, the contents can be easily taken out, and the residue remaining on the inner surface of the package can be significantly reduced. The usable amount of contents can be sufficient. Moreover, according to this invention, the effort and process for taking out the attached content again are unnecessary, and the material collection | recovery of the packaging material after use becomes easy. In addition, according to the present invention, since the packaging body is transparent, it is excellent in contents visibility, and provides a packaging material excellent in workability, environmental performance, and safety for business use and general commercial use. be able to.

Hereinafter, the coextruded multilayer film of the present invention will be described in detail.
The film of the present invention is a coextruded multilayer film composed of two or more layers in which a gas barrier layer and a heat seal layer are disposed. When a packaging body filled with the contents is produced, the heat seal layer is the contents. Used on the side.
Further, the film of the present invention can be used as a single product or laminated with another film to form a bag for packaging contents, a deep-drawn bottom material, and a lid material.

<Heat seal layer>
The heat seal layer of the film of the present invention is disposed on the content side and directly contacts the content when a package body filled with the content is prepared.
As the resin constituting the heat seal layer, a polyolefin resin or a resin composition containing a polyolefin resin as a main component can be used.
The type of polyolefin resin is not particularly limited, but low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene, medium density polyethylene, high density polyethylene (HDPE), ultra high density polyethylene, polypropylene ( PP), a copolymer composed of an α-olefin having 1 to 20 carbon atoms, and the like can be used. These may be used alone or in combination of two or more. Among these, from the viewpoint of heat sealability, it is desirable to use low density polyethylene or linear low density polyethylene.

Moreover, when using the film of this invention for the bottom material and lid | cover material of deep drawing packaging, when opening a packaging material by comprising a heat-seal layer by mixing 2 or more types of incompatible polyolefin resin. In addition, the heat seal layer cohesively breaks, and the specification can be easily opened (easy peel) by hand without using a blade.
The combination of resins imparting an easy opening function is not particularly limited, and examples thereof include mixing of a polyethylene resin and a polypropylene resin, mixing of a polyethylene resin and polybutene, and mixing of a polypropylene resin and polybutene. For example, mixing of LLDPE and polybutene, mixing of PP and LDPE, mixing of PP and ethylene-vinyl acetate copolymer (EVA), mixing of PP and ethylene-acrylic acid copolymer (EAA), mixing of PP and ionomer, Examples thereof include a mixture of PP and ethylene-methyl methacrylic acid copolymer (EMMA). Among these, a mixture of LLDPE and polybutene or a mixture of PP and LDPE can be suitably used. The mass mixing ratio of these resins is preferably 30:70 to 70:30, and more preferably 40:60 to 60:40.

The heat seal layer surface of the film of the present invention has a three-dimensional surface roughness Ra per 6700 μm ² of 300 nm to 1000 nm. Ra is the arithmetic average roughness.
The lower limit of Ra is more preferably 400 nm or more, further preferably 600 nm or more, and the upper limit is more preferably 800 nm or less.
When the film has an Ra of less than 300 nm, contents such as eggplant and miso are not easily separated from the film, and in particular in the case of foods of 1 × 10 ⁵ mPa · s or more, the residue remains significantly. On the other hand, if the thickness exceeds Ra 1000 nm, the heat seal does not adhere to the entire surface and bubbles are generated.
The three-dimensional surface roughness Ra of the film of the present invention can be measured with an optical interference type non-contact surface roughness meter in accordance with ISO25178, and an area of 6700 μm ² is measured.

  As a method for making the heat seal layer surface into an embossed pattern shape having a predetermined roughness range, there is no particular limitation, but it is important that the heat seal layer surface can form continuous concavity and convexity on the surface, known embossing, Examples include blasting.

  In the embossing process, an embossing roll is heat-pressed on the surface of the heat-sealed layer of the coextruded film to transfer the uneven shape on the surface of the embossing roll to the film surface. The embossing may be performed before winding the coextruded film, or may be performed after winding the film once. From the standpoint of continuous film production, it is desirable to emboss between coextrusion film formation and winding. In any case, the conditions of the embossing roll surface shape, the embossing roll contact pressure, and the film temperature are appropriately combined so that the surface roughness of the film heat seal layer surface is within a predetermined range.

  As the pattern of the embossing roll, a known pattern such as a lattice pattern, a mesh pattern, and a satin pattern can be used. For example, a # 50 mesh to a # 200 mesh can be used. Moreover, the embossing roll which gave the blast process can also be used. The height difference of the unevenness of the embossing roll is about 1 to 100 μm in terms of releasability.

  In the blast processing, irregularities are formed on the film surface by spraying abrasive particles such as glass on the surface of the heat seal layer of the coextruded film. The blasting process may be performed before winding the coextruded film, or may be performed after winding the film once. From the viewpoint of continuous film production, it is desirable to perform blasting between coextrusion film formation and winding. In either case, the surface roughness of the film heat seal layer surface is set within a predetermined range by appropriately combining the type and particle size of the abrasive and the spraying conditions.

  The shape of the heat seal layer surface of the film of the present invention is preferably an embossed pattern. In the present invention, the “embossed pattern shape” means a state having a continuous uneven shape on one surface, and can be formed by embossing.

For the purpose of further improving the releasability with the contents, a release agent may be added to the heat seal layer. As the release agent, known ones can be used, and for example, fatty acid esters, silicone oils, and the like can be appropriately selected according to the contents.
The lower limit of the content ratio of the release agent relative to the entire heat seal layer is preferably 1% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more from the viewpoint of obtaining releasability. The upper limit is preferably 40% by mass or less, and more preferably 30% by mass or less from the viewpoint of suppressing bleeding out of the release agent.

  The thickness of the heat seal layer of the film of the present invention is 2 μm or more, preferably 3 μm or more, more preferably 4 μm or more, and 15 μm or less, preferably 12 μm or less, more preferably from the viewpoint of film forming properties and peel appearance. It is desirable that the thickness be 10 μm or less. By setting the lower limit of the layer thickness to 2 μm or more, stable film-forming properties can be obtained, and by setting the upper limit of the layer thickness to 15 μm or less, fluffing of the peeled surface and film residue can hardly occur, and good A good peel appearance.

<Gas barrier layer>
In the film of the present invention, one or more gas barrier layers are disposed. When a plurality of gas barrier layers are provided, the same configuration or different configurations may be used, and the plurality of gas barrier layers may or may not be adjacent to each other.
Although the resin constituting the gas barrier layer is not particularly limited, for example, a polyamide resin is preferable in that it can impart not only oxygen barrier properties but also pinhole resistance to the film. Specifically, 6-nylon (6Ny), 66-nylon (66Ny), 6-66 nylon (6-66Ny), 12-nylon (12Ny), MXD6 obtained by polycondensation of metaxylenediamine and adipic acid Nylon (MXD6Ny), a mixture thereof, and the like can be used, and can be appropriately selected according to the purpose of use. For example, 6Ny and 6-66Ny are preferable when high pinhole resistance is required, and MXD6Ny or a mixture of MXD6Ny and 6Ny is preferable when high oxygen barrier properties are required.
As the resin constituting the gas barrier layer, ethylene-vinyl acetate copolymer saponified product (EVOH) is also preferable because it has high gas barrier properties.
Furthermore, both a polyamide resin layer and an EVOH layer can be used.

The lower limit of the thickness of the polyamide resin layer is preferably 5 μm or more and more preferably 8 μm or more from the viewpoint of obtaining good pinhole resistance. Further, from the viewpoint of moldability, the upper limit is preferably 150 μm or less, and more preferably 100 μm or less.
The thickness of the EVOH layer is not particularly limited, but the lower limit is preferably 3 μm or more, more preferably 5 μm or more from the viewpoint of obtaining sufficient oxygen barrier properties. Further, the upper limit is preferably 40 μm or less, more preferably 35 μm or less, from the viewpoint of combining good film coextrusibility and film strength.

<Polyolefin resin layer (outer layer) on gas barrier layer surface>
The film of this invention can arrange | position a polyolefin resin layer (outer layer) on the gas barrier layer on the opposite side to a heat seal layer.
The polyolefin resin is not particularly limited. For example, polyethylene resins such as low density polyethylene, linear low density polyethylene, ultra low density polyethylene, medium density polyethylene, high density polyethylene, and ultra high density polyethylene, homopolypropylene, Examples thereof include polypropylene resins such as propylene-ethylene copolymers.
For example, when a polyethylene resin layer is disposed on the outer layer, the low temperature impact resistance and pinhole resistance of the film of the present invention can be improved. Among these, linear low density polyethylene can be preferably used.
Further, for example, when a polypropylene resin layer is disposed on the outer layer, the film can be given a suitable stiffness, and bag-making suitability and the like can be improved.

  The lower limit of the thickness of the polyolefin resin layer is preferably 5 μm or more, and more preferably 10 μm or more in order to impart impact resistance, appropriate stiffness, etc. to the film. In addition, the upper limit is preferably 150 μm or less, and more preferably 100 μm or less, from the viewpoint of designing the physical properties of the film by arranging the gas barrier layer and the heat seal layer in a balanced manner.

<Adhesive resin layer>
Since the film of the present invention improves interlayer adhesion with the heat seal layer, gas barrier layer, and outer layer, an adhesive resin layer can be appropriately disposed between the layers. Further, when a polyolefin-based adhesive resin layer is disposed on both sides of the gas barrier layer that is vulnerable to bending, the pinhole resistance of the entire film can be improved.
Since the heat seal layer and the outer layer are composed of a polyolefin resin, a polyolefin-based adhesive resin is suitable as the adhesive resin to be used. For example, a modified polyolefin resin grafted with at least one monomer selected from unsaturated carboxylic acids or derivatives thereof can be suitably used.

<Additives>
The film of the present invention is an inorganic particle such as silica, talc, kaolin, calcium carbonate, or the like for the purpose of improving and adjusting various properties such as molding processability and productivity within a range that does not significantly impair the effects of the present invention. Appropriate additives such as pigments such as titanium and carbon black, flame retardants, weather resistance stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, crosslinking agents, lubricants, nucleating agents, plasticizers, anti-aging agents, etc. Can be added. In order to maintain good transparency of the film, the particle diameter of inorganic particles and lubricants is preferably 100 μm or less.

<Film structure>
The film of the present invention is a coextruded multilayer film composed of two or more layers of gas barrier layer / heat seal layer. As a preferable layer structure, the description of the adhesive resin layer is omitted, and a structure of three layers or more of an outer layer / a gas barrier layer / a heat seal layer is used.
In addition, PA is a polyamide resin, PO is a polyolefin resin, PE is a polyethylene resin, PP is a polypropylene resin, EVOH is a saponified ethylene-vinyl acetate copolymer, and an easy peel layer composed of a mixture of polyolefin resins is abbreviated as EP. I write.
Among these, the configurations (3), (6), (9), and (12) can be preferably used.
(1) PA / PO
(2) PA / EVOH / PO
(3) PE / PA / PO
(4) {PE or PP} / PA / PO
(5) {PE or PP} / EVOH / PO
(6) {PE or PP} / PA / EVOH / PA / PO
(7) PA / PO / EP
(8) PA / EVOH / PO / EP
(9) {PE or PP} / PA / PO / EP
(10) {PE or PP} / PA / PO / EP
(11) {PE or PP} / EVOH / PO / EP
(12) {PE or PP} / PA / EVOH / PA / PO / EP

  The total thickness of the film of the present invention can be appropriately selected in the range of about 80 to 300 μm depending on the shape, weight, required gas barrier performance, packaging form and the like of the contents.

The film of the present invention is produced by a known coextrusion method. Examples of the coextrusion method include a T-die method and an inflation method.
The film of the present invention can be produced by any of non-stretching, uniaxial stretching, and biaxial stretching depending on the application.
Further, the film of the present invention can be used alone or can be used by being laminated with other films. For example, for bags and lids, when a stretched film such as a biaxially stretched polypropylene film or a biaxially stretched polyethylene terephthalate film is laminated on the unstretched film of the present invention, an appropriate stiffness can be imparted. Is preferred. For deep-drawn bottom materials, it is preferable to use the film of the present invention as an unstretched film from the viewpoint of moldability.

  Examples of the package using the film of the present invention include bags and deep drawn packages. The package can be manufactured by a known pillow packaging machine, three-side seal packaging machine, deep drawing packaging machine, or the like.

Examples The present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
A non-stretched coextruded film having a layer structure described in each example was formed, and then an embossing roll was pressure-bonded to the heat seal layer surface at a temperature of 120 ° C. and a pressure of 40 kg / cm ² to transfer the embossed pattern, I took it.
The embossing roll used in each example is blasted and has a roll surface roughness Ra of (A) roll of 1880 nm, (B) roll of 7730 nm, and (C) roll of 990 nm.

In addition, the layer structure of each example is described in order from the outer layer side to the heat seal layer side, and the components of each layer are described by the following abbreviations. “+” Means mixing of resins.
PE: Polyethylene resin PP: Polypropylene resin PB: Polybutene resin Ny: Nylon 6
EVOH: Saponified ethylene-vinyl acetate copolymer AD: Carboxylic acid-modified ethylene-vinyl acetate copolymer (adhesive resin)

<Examples 1 and 2>
PE / AD / Ny / AD / PE (layer thickness 30 μm / 10 μm / 15 μm / 10 μm / 35 μm, total thickness 100 μm)
The embossing roll (A) was used in Example 1, and the embossing roll (B) was used in Example 2.

<Examples 3 and 4>
PE / AD / Ny / AD / PE / PE + PB (layer thickness 90 μm / 20 μm / 40 μm / 20 μm / 90 μm / 10 μm, total thickness 280 μm)
The mixing ratio of PE + PB is 50: 50% by mass.
In Example 3, an embossing roll (A) was used, and in Example 4, an embossing roll (B) was used.

<Examples 5 and 6>
Ny / AD / PE + fatty acid ester (layer thickness 100 μm / 20 μm / 80 μm, total thickness 200 μm)
The mixing ratio of PE + fatty acid ester is 70: 30% by mass.
In Example 5, an embossing roll (A) was used, and in Example 6, an embossing roll (B) was used.

<Examples 7 and 8>
PP / AD / Ny / EVOH / AD / PP (layer thickness 40 μm / 15 μm / 10 μm / 10 μm / 10 μm / 60 μm, total thickness 140 μm)
The embossing roll (A) was used in Example 7, and the embossing roll (B) was used in Example 8.

<Comparative Example 1>
A coextruded multilayer film having the same layer structure as in Example 1 was formed, and embossing was not performed.

<Comparative example 2>
A coextruded multilayer film having the same layer configuration as that of Example 1 was formed, and an embossing roll (C) was used.

<Comparative Example 3>
A coextruded multilayer film having the same layer structure as in Examples 3 and 4 was formed, and embossing was not performed.

<Comparative example 4>
A coextruded multilayer film having the same layer structure as in Examples 5 and 6 was formed, and embossing was not performed.

<Comparative Example 5>
A coextruded multilayer film having the same layer structure as in Examples 7 and 8 was formed, and embossing was not performed.

<Evaluation>
The film obtained in each example was evaluated as follows and summarized in Table 1.
(1) 3D surface roughness Ra
Arithmetic mean roughness per measurement area 6700 μm ² (93.97 μm × 71.3 μm square) in accordance with ISO25178 using Ryoka System optical interference non-contact surface measurement system “VertScan” for the heat seal layer surface of the film Ra was measured.

(2) Non-adhesiveness of the contents to the film (film release properties)
Prepare 2 sheets of 5cm square film, and sandwich 10g of sardine (Imuraya "750g Koshian") with a viscosity of 1x10 ⁵ mPa · s or more between the heat seal layers of the upper and lower films. The sample was placed on a horizontal table, and a 5 cm square 3 kg weight was placed thereon and allowed to stand at 2 ° C. for 24 hours. Thereafter, the upper film was peeled off.
Measure the area where the wrinkles are attached per 5 cm square of the peeled upper film. If the adhesion area is less than 1%, “◎”, if it is 1% or more but less than 5%, The case of 5% or more was evaluated as “x”.

(3) Transparency of the film The film itself and the case where the strainer was sandwiched were observed with the naked eye.

  From Table 1, Examples 1 to 8, in which the heat seal layer surface of the film had a continuous concavo-convex shape and the three-dimensional surface roughness Ra was 300 nm or more, the adhesion of the wrinkles to the film was small, and The moldability was good. Moreover, in any of the examples, the film was colorless and transparent, had no haze, and the contents were easily visible. Furthermore, by performing the continuous processing from co-extrusion film formation to film roughening, the film roughening could be performed efficiently and stably.

  According to the film of the present invention, high-viscosity food contents such as eggplant, miso, and bread dough can be easily taken out from the packaging material, reducing the amount of food waste and eliminating the need to take out the adhering content again. This improves the work efficiency, makes it easy to collect the packaging materials after use, has good visibility of the contents, is inexpensive for the food processing industry and general consumers, and has excellent workability, environmental friendliness, and safety. Material can be provided.

Claims (5)

A coextruded multilayer film comprising two or more layers, wherein a gas barrier layer and a heat seal layer are disposed, wherein the heat seal layer is composed of a polyolefin resin or a resin composition containing a polyolefin resin as a main component, and the heat When the three-dimensional surface roughness Ra per 6700 μm ^{2 of the} seal layer surface is 300 nm or more and 1000 nm or less, and the package for filling the contents using the film is prepared, the heat seal layer contains the contents. A co-extruded multilayer film characterized by being disposed on the object side.   The coextruded multilayer film according to claim 1, wherein the heat seal layer has an embossed pattern shape on the surface.   The coextruded multilayer film according to claim 1, further comprising a polyolefin resin layer disposed on the gas barrier layer. The package body using the coextruded multilayer film in any one of Claims 1-3 for filling the content more than viscosity 1x10 < ⁵ > mPa * s.   The method for producing a coextruded multilayer film according to any one of claims 1 to 3, wherein the surface of the heat seal layer is embossed.